Where to start looking rifle or shells? can the firing pin /bolt get built up or sticky on them? It isnt my rifle and I have not seen it. Just asking to try and help my nefew. Thanks

If it's factory ammo, just try another box of a different lot number if possible.. If misfires still occur, then begin the process of elimination with the rifle..

It can be several different or concurrent factors such as weak striker spring (resulting from storing firearm with a cocked striker), something impeding the full movement of the bolt handle into the down position, a piece of primer or crap that got into the striker recess and interfering with full forward travel, etc., etc...

Check for gummy lub residue and rust inside the bolt and around the firing pin and spring. This has been the source of most of the ignition problems I have seen. A fresh firing pin spring wouldn't hurt and is cheap insurance.

with an A-bolt the most likely place to start (on the rifle) is the safety bar partially blocking the striker. It falls away passively and anything that impedes it's progress will result in a decreased firing pin fall.